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Reg. 203, Reg. 204, Reg. 205, Reg. 206
STAYS

Stresses in steel jointed stays

a) The section of least strength whether of stay, rivets, shackle or pin shall be used in calculating the working pressure for the stay. For parts in tension a stress of 9,000 lbs. per square inch of net section shall be allowed, and for parts in shear stress of 8,000 lbs. per square inch of net section,
b) Parts as in double shear shall be allowed a section of 1.875 times the single section.


Reg. 204
STAYS


Stay Tubes

For stay tubes, whether of wrought iron or steel, seamless or electric resistance welded or lap-welded the maximum working pressure shall be calculated from the following formula :-

 

W. P. = 5900 [ ( D - 1.28 )2 - D12 ] Eqn.(41)
A (N)

where
D = the diameter of the tube over threads in inches,

D1 = the internal diameter of the tube under the threads in inches

N = the number of threads of stay per inch.

A is the area in square inches supported by one stay tube, measured from centre to centre of stay tubes. When the area contains tubes or parts of tubes their aggregate area, calculated from their smallest external diameter of body when in tension and smallest internal diameter when in compression, shall be deducted from the area of the containing figure and the remainder used as A in the formula.


Reg. 205
STAYS

Stays in tension and compression

a) The same stress shall be allowed in compression as in tension. The strength of short stays in compression and not liable to bending shall be calculated on the net section of the stay at bottom of thread or in body, whichever is less.
b) The stress to be allowed on any stay or part of a stay not provided for in foregoing shall be the same as that allowed for stays or parts of stays of approximately like kind in similar conditions.


Reg. 206
STAYS

Measurements of stayed areas in the end plates of Locotype and Vertical Boilers

When the areas supported by stays are semi-circular as in the upper parts of the end plates and smokebox tube plates of locotype boilers, or annular as in the crown plates of vertical type boilers, the area to be supported by stays A in Eqn. 39 and 40 shall, in the first case, be the area of plate contained within the margins credited to casing or barrel sides, screw stays, fire door ring or tube stays as the case may be and in the second case be the area of the annulus between the margins credited to uptake and shell. When bolt staying is necessary the stays shall be properly distributed; the aggregate stay section shall then be used in the formula for calculating the working pressure.
 
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